If you insist on doing the interview in person, why not just tell them ahead of time what their environment needs to do when they get there? Give people instructions and a script (formal or just a numbered list of steps) that determines they're ready to go.
Better yet, just don't make people do that stuff in your office.
Why bother videorecording interviews at all? I'd have problems writing a line of code with someone breathing down my neck. If you did it to me on the job, I'd chase you out of the room. I feel like a lot of these problems are, like I said, unforced.
Agree to disagree about the degree of difficulty of getting clean environments to candidates. You're either serious about recruiting as an engineering problem or you're not. "Not" is fine, but then don't pretend like there's some kind of rigor in deciding which corners you're willing to cut.
I'm not making this stuff up; this is how we've been hiring people for about 10 years now, and every time I hear someone explain how challenging or untenable our process is, I keep wondering, "what am I doing wrong to make this work so well for us?"
